This invention relates to a kit of parts for forming a fiber optic assembly, comprising a stack of two or more panels each of which is provided with retaining means for securing connectors for optical fibers, to an assembly comprising the panels and the installed connectors, and to a method of making the assembly. In particular, the invention relates to a kit of parts, and formed assembly, suitable for use as a stack of patch panels in a closure, a cabinet, a sub-rack or other container, for example in a patching shelf of the exchange rack in a telecommunications network.
The process of connecting one length of optical fiber to another by means of an intermediate length of optical fiber is known in the art as xe2x80x9cpatchingxe2x80x9d. The intermediate lengths of optical fiber are generally in the form of pigtails, and the pigtails are generally held on a panel, known as a xe2x80x9cpatch panelxe2x80x9d, to secure them, and for protection. A pigtail is an optical fiber which is pre-terminated at one or both ends, for easy insertion into a connector. Where the optical fiber is terminated at only one end, the other end is left free for splicing to a main length of optical fiber. A major advantage of using intermediate lengths of optical fiber in the form of pigtails, on a patch panel to join main lengths of fiber; is that it is possible to move or interchange connections between optical fibers in order to modify a network, without handling the main lengths of cable. This reduces the risk of damage to the main lengths of fiber. The short pigtail sections can easily be replaced, if damaged.
The use of two or more stacking patch panels, e.g. in a sub-rack, and the use of two or more stacking splice trays in a closure are known. WO-A-95/29418 (Raychem Limited) describes a plurality of patch panel trays, that are hinged together along their rear edges to allow access to each tray. Each tray has a lip extending around its periphery, and is provided with a row of upstanding projections for retaining eight connectors therebetween. Each tray rests on the lip of the adjacent tray. The row of connectors extends from the rear to the front of the tray, but neither the connectors nor the upstanding projections project in height above the height of the lip around each panel. The patch panel trays of WO-A-95/29418 are intended to be used in groups which are mounted in a frame or support. The support may be a drawer in which the trays are hinged, and the drawer itself may be slideably mounted in a shelf in a rack.
The shelf and rack support arrangement as described in WO-A-95/29418 is a typical arrangement in telecommunications networks. The shelves and racks are usually a standard size, and therefore there are dimensional limitations on the size of each panel, and for any given height of panel, on the number of panels that can be stacked one above the other in the shelves and racks.
EP 0 557 187 (A) and U.S. Pat. No. 5,363,466 disclose an optical fiber assembly comprising a stack of flat modules, each of which is hingedly connected to a support. The modules are arranged to receive and hold optical fiber connections.
We have invented a new kit of parts for forming an optical fiber assembly, an assembly so formed, and a method of making the assembly, which allows an increased number of fiber optic connectors to be stored in a stack of panels, without increasing the overall size of the stack. In other words, increased capacity is achieved, without increased volume.
A first aspect of the present invention provides a kit of parts for forming an optical fiber assembly, the kit comprising:
a) two or more panels, including a base panel and one or more further panels, each panel having a body and an upstanding edge, and
b) stacking means for stacking the panels,
which assembly is characterised in that each of the panels has a plurality of connector-retaining means for securing optical fiber connectors, which connector-retaining means extend beyond the upstanding edge, in that each of the panels has an opening or recess in its body, and in that the stacking means are arranged for stacking the panels such that the connector-retaining means of each panel project into the opening or recess in the adjacent panel thus allowing the adjacent panel to rest on the upstanding edge.
Another aspect of the invention provides the assembled kit of parts. Thus a second aspect of the invention provides an optical fiber assembly comprising two or more panels, including a base panel and one or more further panels, each panel having a body and an upstanding edge, and a stacking means for stacking the panel, in that each of the panels has a plurality of connector-retaining means for securing optical fiber connectors, which connector-retaing means extend beyond the upstanding edge, characterised in that each of the panels has an opening or recess in its body, and in that the stacking means are arranged for stacking the panels such that the connector-retaining means of each panel project into the opening or recess in the adjacent panel, thus allowing the adjacent panel to rest on the upstanding edge.
Although the present invention envisages that the stack of panels could comprise only two panels, usually there would be more panels. A particularly preferred embodiment uses six panels.
The present invention refers to a base panel, and further panels on the base panel. These will usually be above the base panel. However they could be below the base panel, or the base and further panels may be on their sides. For convenience in this specification, reference may be made to orientations such as above, below, up, down, etc. These will be made with reference to a base panel beneath further panels. It will be appreciated that other orientations are possible, and encompassed by this invention. It is the relative positions of the panels that is important, and the term xe2x80x9cbase panelxe2x80x9d is used to designate the starting point panel, wherever it may be (above, below, to the side) relative to the further panels.
The connector-retaining means in each panel are offset laterally (i.e., in the plane of each panel) relative to the connector-retaining means in the adjacent panel. The openings or recesses in each panel will usually also be similarly offset.
In a preferred embodiment the connector-retaining means comprise projections, e.g., projecting stubs. These project upwards from the plane of each panel, and are of such a height, that when the panels are stacked they project through the opening in the adjacent panel. The base panel, where it is beneath the further panels, has no projecting connector. retaining means attempting to project through it, and therefore it need not contain an opening. However, it may do so, and this may be preferred to minimize inventory. Also, as mentioned above, the base panel may be above the further panels, and the connector retaining means may project downwards rather than upwards from the plane of each panel.
The connector-retaining means are preferably arranged to be of such a height that they are slightly higher than a connector, when inserted.
In other embodiments, the connector-retaining means may comprise an adapter which fits between the projections to enhance retention of the connectors. One design of adapter is in the shape of a double open ended box, having one dimension, in cross-section, longer than the other. The adapter fits, preferably with the aid of spring clips, between the retaining projections. The adapter is shaped to fit around a standard, known, connector, which has a correspondingly rectangular cross-section. Preferably the adapter is arranged so that its shorter dimension, in cross-section, extends in the plane of each panel.
In preferred embodiments, each panel comprises a lip around, or near its edge, and when the panels are stacked, each panel is preferably arranged to rest on the lip of the adjacent panel. In these embodiments, when the connector-retaining means are in the form of projections, the projections on any particular panel preferably extend to a height greater than the height of the lip of that panel.
Each panel is preferably generally rectilinear having a rear edge, a front edge, and side edges, and the connector-retaining means preferably extend across the panel from the rear edge to the front edge in a substantially straight line. The line of connector-retaining means preferably extends substantially parallel to the side edges of the substantially rectilinear panel. Other configurations, e.g., a line of connector retaining means extending diagonally across the panel, or in random configuration are also possible, provided they are offset relative to those in the adjacent panel, and arranged to project into the opening in the adjacent panel. If necessary, more than one opening may be provided in the panels to accommodate the projecting connector-retaining means. The generally rectilinear panel may have rounded corners.
In a particularly preferred embodiment, each panel is substantially rectilinear, with a straight line of connector-retaining means extending from the rear to from face of the panel to one side of the panel, i.e., not through the center of the panel. The opening in the adjacent panel is an elongate opening corresponding to the position of the line of connector-retaining means in the lower panel, in order to accommodate the portions which project through it.
It is especially preferred for each of the further panels, and optionally also the base panel, in the stack to be substantially the same size, and preferably to be substantially identical. For example, they may be as described in the preceding paragraph, each panel being rotated 180xc2x0 relative to its neighbor, so that the projecting connector-retaining means in each panel align with the openings in the adjacent panel. Panels in layers 1,3,5, etc. of the stack will be identically aligned. Similarly panels in layers 2,4,6 etc. of the stack will be identically aligned. The use of substantially identical panels minimizes. inventory.
In the kit of parts according to the invention, the means for stacking the panels may comprise interlocking parts on each panel which engage the adjacent panel, or it may comprise a separate member, which itself engages each of the panels. Preferably the means for stacking the panels, whether on each panel, or a separate member, comprises one or more hinges. When the panels are substantially rectilinear, the panels are preferably hinged along their rear edges.
The formed assembly according to the invention may also comprise fiber optic connectors retained in at least some of the connector-retaining means. In this case, not only the connector-retaining means, but also part of the connectors themselves, may project through the opening in the adjacent panel. Whether or not this occurs depends on the type of connector used.
Certain connectors that are typically used in patch panels are, in cross-section, longer in one dimension than in the perpendicular direction. In prior art arrangements, on patch panels, these connectors have traditionally been arranged so that the longer dimension extends in the plane of the panel. With this arrangement it was possible to arrange eight connectors across each panel, and to stack together six panels to fit in a standard shelf in a rack. With the present invention, it is possible to use those same connectors and the same sized panels, but to arrange the connectors so that their longer dimension extends substantially perpendicular to the plane of the panel. By doing this it is possible to fit twelve connectors across each panel. Although the height of each connector is now increased, the height of each panel does not need to be increased, since the projecting part of the connector projects into the plane of the neighbouring panel. Therefore, even with the new arrangement, it is still possible to fit six panels together in the shelf in the rack. Thus the capacity of the six panel stack is increased from 48 (eight in each panel) in the prior art to 72 (twelve in each panel) in the present invention, without altering the overall size of the stack. Furthermore, standard components, e.g., the same connectors, may be used.
In certain embodiments according to the invention, modular panels are used. For example, a main body portion may be pre-installed with connector retaining means, and add-on modules such as splicing spools, or islands for pigtail storage and bend control, may be fitted to the main body portion. Advantageously the modules may be a snap fit together.
The invention also provides a method of forming an optical fiber assembly comprising:
a) providing two or more panels, each panel having a body and an upstanding edge, and
b) stacking the panels, characterised in that
each of the panels has a plurality of connector-retaining means for securing optical fiber connectors, which connector-retaining means extend beyond the upstanding edge, in that
each of the panels has an opening or recess in its body, and in that the stacking is carried out such that the connector-retaining means of each
panel project into the opening or recess in the adjacent panel.